Split Preview:
Provides the feature to open Content Preview on IFrame Instead of default redirect and open on independent page.

This Module provides the Split Feature, Split the preview page on different page layouts, mobile, Tablet and Desktop view.

Configuration:
Enable the module Split Preview (drush en split_preview).

Login as admin user, Go to Administrator menu => Structure => Content Types => Select Any Content Type => Edit Content Type => Then select the radio button preview optional or required.